An important segment of advanced materials and nanotechnology is conjugated polymers, or conducting polymers. Conducting polymers are important for their electronic and optical properties, and one particularly important material property is electronic conductivity. This electronic conductivity can be controlled by doping, wherein charge sites, whether positive or negative, are introduced onto the polymer chain which typically increases conductivity. It is important to be able to control the doping process. For example, it would be useful to be able to adopt conditions wherein the doping reaction is known to occur, and adopt other conditions wherein the doping reaction does not occur. For example, it would be useful to transport and store compositions for later use which are substantially unreactive to doping until a doping reaction is desired to increase conductivity. Also, the doping reaction can create ion pairs which alter the polarity and solvability of the conductive polymer. Hence, a doped polymer can be insoluble in many solvents due to the ionic character and other factors. This insolubility can result in limited processability in the doped state and limit commercialization.
Regioregular polythiophenes, both homopolymers and various kinds of copolymers and terpolymers, are a particularly important example of conducting polymers. See, for example, Katz et al., Acc. Chem. Research, 2001, 34, 359-369; McCullough, Adv. Mater., 1998, 10, No. 2, 93-116; McCullough et al., chapter 9 in Handbook of Conducting Polymers, 2nd Ed., 1998. Controlled doping of regioregular polythiophenes would further enable their commercialization. More refined formulation strategies are needed which can be tailored to particular applications.